1. Field of the Invention
This invention relates to an improved screwdriver and screw which can be used in combination or alone, the improved screwdriver and screw having curvilinear contact surfaces which provide more contact area when engaging a screw or screwdriver.
2. Description of the Prior Art
In most conventional screws and screwdrivers, only the corners of the driver blade contact the slot. Because of the wedge shape of most blades, this contact will usually be at the top edges of the slot where there is minute surface area. The screw slot may be severely damaged at these points of contact where high forces are encountered during torque. The screwdriver may also "cam-out" or ride up and out of the screw slot because of the low surface area contact. This is especially true after the slot has been damaged.
Screwdrivers and screws are disclosed in a number of issued patents with increased surface area contact between the blade and slot. The problem with these designs is that only specially designed screwdrivers can be used to engage specially designed screws. Most of the prior art screws and screwdrivers are shaped to correspond to each other so that they are closely engaged. Use of the these screwdrivers with conventional screws or vice versa would be inadequate if not inferior.
There are other prior art patents which disclose screw slots having different constructions that can be used with conventional screwdrivers. However, these designs deal primarily with the ease of inserting the blade into the slot.